This invention relates to acceleration sensing apparatus and more particularly to a sensor operable in response to a predetermined acceleration to energize an electrical circuit and permit apparatus such as a vehicle passenger restraint device to be actuated.
Vehicle manufacturers currently are concerned with the protection of vehicle occupants in the event the vehicle should be involved in a crash. One proposed protective device is an inflatable bag which, upon rapid deceleration of the vehicle, inflates quickly so as to restrain movement of the vehicle's occupants and protect them against injury. The inflation of the bag depends upon operation of an actuating mechanism triggered by the operation of a sensor which detects the deceleration of the vehicle. If the occupant restraining device is to be successful in operation, the vehicle must be equipped with several triggering sensors that are mounted at a number of different points on the vehicle and in such locations as to be operated very early in the progress of a crash. For example, a triggering sensor may be mounted on the front bumper of a vehicle so as to be operated by the deceleration of the bumper which may occur prior to appreciable deceleration of the vehicle's occupants. In such an arrangement, the restraining bag will be inflated in sufficient time to protect the occupant.
Although triggering sensors of the kind referred to are capable of functioning satisfactorily, care must be taken to prevent actuation of the restraining mechanism in which an occupant of a vehicle requires no protection. For example, a vehicle's bumper may be displaced at a sufficiently rapid rate of speed to operate the trigger sensor, but the displacement of the bumper could be absorbed in such manner that the passenger compartment of the vehicle would not be subjected to sufficient deceleration as to cause injury to its occupant. In addition, it is desirable that means be provided in conjunction with the restraint mechanism to prevent actuation thereof by vandals.
An object of this invention is to provide an acceleration sensing device for use in conjunction with one or more sensors which trigger operation of a vehicle's occupant restraining mechanism and which prevents operation of such mechanism except in those instances in which its operation is desired.
Another object of the invention is to provide an acceleration sensor of the kind referred to which may be mounted on a vehicle in or near the passenger compartment so as to be subjected to the same acceleration forces as the latter.
A further object of the invention is to provide an acceleration sensor which is of small size, of simple construction, and reliable in operation.